Hey Cato, sounds like you have alot of questions. You certainly came to the right place to get them answered as many people on this site have years of experience with all types of dslrs. I mostly shoot film, so please take that into consideration when reading my response. I am looking into getting a DLSR and have some of the same questions as you. The thing that jumped out at me concerning DLSRs is that some perform better than others in low light situations. I would suggest you go to the top of the website and browse reviews, check out the pro reviews as well.